The invention relates to a pivoting air lock for the entry and/or exit of a substrate from one treatment chamber into an adjacent one, or from atmospheric space into a chamber of lower pressure, especially a slot air lock for a pass-through vacuum coating apparatus, having a gate-like valve plate held in stationary bearings and a closing motor actively connected to the valve plate, and a frame-like sealing element surrounding the air lock opening.
DE-OS 39 41 502 has disclosed a loading and unloading chamber apparatus, having a low-pressure chamber, a transport mechanism provided within the low-pressure chamber in question for the transport of a substrate holder in plate form suitable for the releasable mounting of substrates, having an exhaust connection for exhausting the chamber to a low pressure, and with a gas inlet connection for the introduction of a gas in order to return the evacuated chamber to an atmospheric pressure.
In this known apparatus, an air lock valve is provided on both sides of the low-pressure chamber, and the valve plate has an elongated, parallelepipedal shape and is affixed to three bearing brackets through which a shaft is brought, which in turn is connected to levers which can be operated by a motor through a rack-and-pinion drive. The valve plate is held so as to be able to turn with respect to the levers fulcrumed on stationary bearings, so that the sealing surface of the valve plate can be pressed against the sealing surface on the housing of the low-pressure chamber, while the valve plate can be aligned to a certain extent with the plane of the housing sealing surface.
In practice, it has been found that the known valve system or known air lock valve fails to meet the most stringent sealing requirements because the necessary sealing ring is stressed unevenly since the sealing plate and drive shaft flex to a certain extent while in the closed state, but especially when the air lock plate has an extreme width-to-length ratio, and when the individual parts of the air lock valve are not very sturdy--and consequently heavy--and are not of extremely high quality material.